<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			*{
				margin: 0;
				padding: 0;
			}
			
			html,body{
				height: 100%;
				overflow: hidden;
			}
			
			#wrap{
				width: 40px;
				height: 300px;
				border: 1px solid;
				margin: 100px auto;
				overflow: hidden;
			}
			#wrap > .inner{
				height: 600px;
				background:repeating-linear-gradient(135deg,black 0px,black 10px,white 10px,white 20px);
			}
			
		</style>
	</head>
	<body>
		<div id="wrap">
			<div class="inner"></div>
		</div>
	</body>
	<script type="text/javascript">
		var inner = document.querySelector("#wrap > .inner");
		var flag =0;
		
		setInterval(function(){
			flag++;
			if(flag==300){
				flag=0;
			}
			inner.style.marginTop = -flag+"px";
		},1000/60)
		
	</script>
</html>
